# Self-Contained Runtime Bundle Distribution

**Status:**
- proposed: 2026-08-10
- accepted: 2026-08-10
- rejected: -
- superseded: -

**Decision [accepted]:** Werkator is distributed for hosts without a Java runtime as a self-contained runtime bundle — a jlink-trimmed JRE plus `werkator.jar` plus a launcher script in one tarball, built by `./gradlew runtimeBundle`.
The JAR stays the primary artifact; a GraalVM native image and a containerized Werkator runtime were rejected.

## Context and Problem Statement

Werkator must run on Hostsharing container servers (the primary target, see ADR 0005).
These hosts provide git, Docker, make, and systemd user sessions, but no Java runtime, and nothing may be installed system-wide.
`docs/bootstrapping.md` sketched a containerized Werkator runtime as the future answer; that sketch was never validated against the operational details.

## Considered Options

* jlink runtime bundle (trimmed JRE + jar + launcher, one tarball)
* GraalVM native image (single executable)
* Containerized Werkator runtime (the original `docs/bootstrapping.md` sketch)

### jlink Runtime Bundle

A `jlink`-generated JRE with the pinned module list, the boot jar, and a `bin/werkator` launcher script, packed as `werkator-runtime-linux-x64.tar.gz` (~66 MB) and unpacked to `~/opt/werkator/` on the target host.

Good:

- No production-code changes and plain JVM semantics — no new failure modes.
- git and docker CLIs are used from the host; build worktree paths stay host paths.
- `init --systemd` works unchanged: `java.home` and the running-jar path resolve into the bundle, so the generated unit points at `<bundle>/jre/bin/java` and `<bundle>/lib/werkator.jar` (verified).
- Every JDK 21 ships jlink — no new build-toolchain requirement.

Bad:

- A directory tree, not a single file (still one tarball to copy).
- JVM startup (~1-2 s) instead of native-image startup — irrelevant for a long-running server.
- The jlink image links glibc dynamically, so it is bound to an architecture and a minimum glibc.
  Corrected on 2026-08-11: that minimum is **not** the build machine's glibc, as originally assumed here.
  `jlink` compiles nothing — it copies the JDK vendor's prebuilt binaries out of the jmods, so the floor is the vendor's build environment.
  Measured over all 33 ELF files of the bundle produced by the Temurin 21 toolchain, the highest required symbol version is `GLIBC_2.15`, which every supported distribution exceeds.
  The build machine's glibc only matters if the toolchain resolves to a distribution-packaged JDK instead of Temurin.

### GraalVM Native Image

Rejected because Spring AOT evaluates bean conditions at build time, and Werkator's dual-mode wiring cannot be represented in a single AOT arrangement:
the CLI context runs without web and with `@Profile("!server")` `CliRunner`, while the `server` subcommand starts a second `SpringApplication` with `WebApplicationType.SERVLET` and the `server` profile gating the watcher/metrics/nginx lifecycles.
Whichever profile and web type the AOT processing fixes, the other mode's beans are missing from the binary.
Supporting both would require replacing the profile wiring with runtime guards and collapsing the two context shapes — an invasive rewrite with regression risk for the JVM path, on top of the usual native-image reflection work (Jackson-bound config and persistence classes, picocli).

### Containerized Werkator Runtime

Rejected for operational complexity: the image must bundle git and docker CLIs; the container needs a same-path `$HOME` mount plus a docker-socket mount and uid/gid mapping so that `DockerBuildRunner`'s `--volume $workspace:$workspace` sibling mounts keep working; and the systemd unit must be hand-edited to a `docker run` invocation.
This remains the documented fallback if the runtime bundle ever becomes unworkable.

## Consequences

- `docs/deployment.md` documents the bundle path; the "Future: Docker-based Deployment" section in `docs/bootstrapping.md` is replaced.
- The pinned JDK module list in `build.gradle.kts` must be re-checked (via the documented jdeps command) when dependencies change.
- Deployment and migration for vm4006 follow plan step 15.
